Zeolite, a typical crystalline porous material, is a material that has solid acid properties, ion exchange properties, adsorption/separation properties and molecular pores as a result of its porous structure. In recent years, zeolite membranes have been the subject of much interest for their potential use as separation membranes for water in organic solvents. In such cases, a zeolite membrane is formed on a porous body, and these as a whole function as a separation membrane.
A well-known method for producing a zeolite membrane is the “hydrothermal synthesis” method, in which: a support is contacted with a reaction solution containing the raw material of a zeolite membrane, which is composed mainly of silica source and alumina source; and the silica source and alumina source in the reaction solution are reacted to form the zeolite membrane on the surface of the porous body.
However, when a porous body is suddenly contacted with a reaction solution containing the raw material of a zeolite membrane, pinholes tend to be formed in the formed zeolite separation membrane, thus lowering the separation performance.
Therefore, a generally-used process is one in which: a porous body is contacted with a slurry containing zeolite seed crystals to attach the seed crystals to the porous body before contacting the porous body with a reaction solution containing the raw material of a zeolite membrane to form the zeolite membrane on the porous body; the seed crystal-attached porous body is then contacted with the reaction solution containing the raw material of the zeolite membrane; and the zeolite membrane is thereby formed around the seed crystals on the porous body (for example, see Patent document 1).    Patent document 1: Japanese Patent Application Laid-Open No. 2004-82008